Master Project: 

CMOS-MEMS Accelerometer for Long-Term In Vivo Small Animal Biological Monitoring

DNA sequencing of laboratory mice (genie pig) is ultimately crutical for systems biology research, genetic function discovery, and new treatments development. Blood pressure, body temperature, activity and bio-potential signal (EKG, EEG, EMG, etc.) are generally required by research worker. In order to let genie pigs "freely" moving without distorting any information, a miniature, long-term, reliable bio-sensing implant network with two way telemetry capability is highly desirable to capture those dynamic behavior.

A implant bio-sensing network which consists micro sensor array, two way data telemetry (no wire), RF powering (no battery) and an on chip control unit is proposed. The total size and weight, including packaging, should be 5mm x 5mm and 100mg, respectively. Here we focus on the activity sensor.

Why the activity information is important? Think about it. If the experiment result shows this particular mouse heart rate is higher than others, how can you tell this is caused by more exercise or genome mutation? We need to quantify activity clearly. By comparing acceleration with real time heart rate, biologists can have a better idea about mice activity. 

The commercial sensor is relativity large size and heavy comparing with laboratory mice. Typically, a laboratory mouse weight is about 20g and size is about 8cm (without tail). This sensor weight and size are 2g and 2.5 cm which is about 1/10 body weight and 1/4 body size. Likely, implanting this system might cause post-implant trauma and data distortion.

CMOS-MEMS technology is selected in this application. This technology has the capability to built MEMS device and CMOS sensing circuit on a same chip. This will significantly reduce the system size and weight, also the package overcomplexity.

The activity sensing system is including 2 MEMS devices , and capacitance to voltage converting sensing circuit. Each MEMS device occupied 800um by 700 um, and has 10mg to 4g acceleration sensing range.  

IEEE Sensor 2005 Paper Download <pdf>